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The behavior of imidacloprid was investigated in two paddy plots with conventional release granular formulation and controlled release granular formulation corresponding to before transplanting (BT) treatment and at sowing (AS) treatment (14 days before transplanting) in nursery boxes, respectively. The maximum concentrations of imidacloprid were 30.2 mg/l and 3.0 mg/l in paddy water at 0.5 days after transplanting (DAT), and 278.4 mg/kg and 81.4 mg/kg in 1cm paddy surface soil at 1 DAT for BT and AS treatments, respectively. Dissipation of imidacloprid from paddy water and 1 cm paddy surface soil can be described by biphasic first-order kinetics in the water and single phase first-order kinetics in paddy soil. The half-lives (DT 50 ) of imidacloprid in BT and AS treatments were 2.0 days, 2.4 days during the first phase (7 days) in paddy water, and 12.7 days and 11.0 days in paddy soil, respectively. AS treatment with controlled release granular formulation had lower concentrations of imidacloprid in paddy water and surface soil and has the potential to pose a lower environmental risk than BT treatment with conventional release granular formulation.

An improved simulation model (PCPF-1) has been evaluated for the prediction of the fate of mefenacet in an experimental paddy field. This model simulates the fate and transport of pesticide in paddy water and the top 1 cm of paddy soil. Observed concentrations of mefenacet in the paddy water and the surface soil exponentially decreased from their maximum concentrations of 0.70 mg litre(-1) and 11.3 mg kg(-1), respectively. Predicted mefenacet concentrations both in the water and surface soil were in excellent agreement with those measured during the first 2 weeks after herbicide application, but concentrations in paddy water were appreciably overestimated thereafter. The model simulated mefenacet losses through runoff, percolation and degradation to be respectively 41.9%, 6.4% and 57.3% of applied, and the mass balance error was about -6%. The model simulation implied that drainage and seepage control, especially shortly after application when herbicide concentrations are high, is essential for preventing pesticide losses from paddy fields. In focusing on pesticide concentrations in this early period the PCPF-1 model can be a beneficial tool for risk assessment of pesticide losses and in the evaluation of agricultural management for reducing pesticide pollution associated with paddy rice production.

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Children and adolescents (N = 1,057), divided by gender, at fourth, seventh, and tenth grades, from two mid-sized cities in the United States and in Japan, were surveyed regarding their evaluations of peer group exclusion of atypical peers. Six reasons for atypicality were being aggressive, having an unconventional appearance, acting like a clown, demonstrating cross-gender behavior, being a slow runner, and having a sad personality. Analyses revealed significant effects for age, gender, country membership, and the context of exclusion. With age, children demonstrated context sensitivity, and believed that the excluded child should not change him- or herself to be accepted by the group. Across contexts, girls were less willing to exclude than were boys, and were more tolerant of differences. The context of exclusion had an effect on all forms of judgments about exclusion, and there were very few overall effects for culture. Most children disagreed with the decision to exclude, believed that they were different from the atypical child, and believed that the excluded child should change him- or herself to be accepted by the group. The results support a theory of developmental social cognition in which multiple sources of influence have a significant effect on social decision making involving the exclusion of others.

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